Macrophagous trilobites with hyper-stemmed compound eyes. (Photo source: Major General Scheunemann)
The humble trilobite, the helmet-headed creature that swam in the sea hundreds of millions of years ago, hid an unusual secret – an “excessive eye” unprecedented in the animal kingdom.
By observing X-ray images, researchers have found that specific species of trilobites – extinct arthropods remotely related to crabs – have their own neural network that processes and transmits hundreds of lenses and signals and numerous optic nerves. September 30 in the magazine Scientific Reports.
Related: Why did the trilobites become extinct?
Today’s arthropods, such as dragonflies and mantis shrimps, are known for their powerful compound eyes, which consist of a myriad of eye features called omatidia, each with its own lens like a disco ball.
But, according to new discoveries, trilobites of the familyVacops had much larger and more complex eyes than their modern-day arthropod cousins. Each of his eyes (one on the left and one on the right) had hundreds of lenses. These primary lenses, about a millimeter long, were thousands of times larger than conventional arthropods. Beneath them, like the bulbs in a car’s headlights, are six (or more) structures that resemble a typical compound eye. “So every large bacopedal eye is a high compound eye with 200 compound eyes,” Brigitte Schoenemann, an archaeologist at the University of Cologne in Germany, said in an email to LiveScience.
Trilobites are organisms that lived from the beginning of the Cambrian period (521 million years ago) to the end of the Permian period (252 million years ago) in marine locations. Some may be predators of aquatic worms, although most are scavengers or plankton eaters. Limestone remains from the Cambrian period are commonly found. But despite their ubiquity in the fossil record, scientists still have questions about their physiology and evolutionary history.